Robust hashing could be new tech tool to fight terror online

From rabid terror propaganda to dangerous rumour-mongering, the internet is an archive of inflammatory material that governments as well as social media networks across the world have struggled to contain and cope with. Since mid-2015 to the beginning of this year, Twitter suspended over 1,25,000 accounts linked to Islamic State terror group. Yet organizations promoting terror continue to survive, if not thrive, online .Now, a cutting-edge technology could emerge as the biggest tool to combat the menace. Hany Farid, senior advisor to the US-based Counter Extremism Project, has helped develop a technology called robust hashing which uses a software to identify images, videos, and audio clips by comparing them against a bank of stored content.With robust hashing, content can be taken down as soon as it is identified. “It can be fully automated. The only manual step would be if a service provider wants to check if posted material is by media outlet,” Farid told TOI over email, adding, “We can create a white-list of approved sites and ban all other users.”This is how it works: Machines see an image as a series of 1s and 0s. Images and its components are identified by a unique code, known as a hash. The hash remains the same even if you resize or crop an image. While filtering images, the software compares these hashes against those of a repository of images it already has. A hash match leads to flagging of content.Farid had earlier developed a similar technology for identifying and taking down child pornography. The software, called Photo DNA, was used by social networking giants like Facebook and Twitter. That was in 2013.